1. Field of the Invention
The field of the invention includes dustpans equipped with one or more light sources of a type which will illuminate the surface in front of the dustpan with a low grazing angle light beam that skims along the surface. Such a device is particularly useful for locating and collecting very small hard to find items.
2. Description of the Prior Art
When cleaning dirt or debris from a floor, it is often hard to see everything that needs to be cleaned up. This is especially true for broken glass. The problem is compounded when the debris or glass is on a floor that provides low contrast or the debris is being cleaned under poorly lit conditions.
The problem which is solved is illustrated by a drinking glass broken on the floor. The impact of the glass on the floor may send chards tens of feet in different directions. The chards become a safety hazard if not located and cleaned immediately. In the time period right after the glass is cleaned people are often extra careful where they step and what they wear on their feet. As time passes, people forget about the incident and become less concerned with any safety issues. An unnoticed and removed piece of glass can be a safety hazard for days, weeks, and even months after the incident. The glass becomes a hazard for people in bare feet, crawling babies, and pets.
Another related problem is locating valuable small items which have been dropped onto the floor. Examples of such items are a contact lens, backs of earrings, and other jewelry parts.
A solution to the problem requires a means for locating the small items and a means for collecting the items once located.
One type of solution that has been proposed is a vacuum cleaner with integral lights. U.S. Pat. Nos. 1,996,934, 2,088,482, 2,208,523, and 2,594,524 describe devices involving placing lights on a suction cleaning device. This type of device is certainly valuable, but has several drawbacks. First, the lights are not particularly designed to make small particles stand out from the background. Second, a suction device is well suited to the situation requiring general clean up of debris, but not to the situation where it is desired to locate and recover valuable items such as a lost contact lens or jewelry part without damaging the item. Third, the suction device is ineffective at cleaning very small particles from a hard floor, since the suction may not be strong enough to lift the small particles and the brushes do a poor job of scooping up the chards from a hard floor.
For many years the concept of illuminating an object with a low grazing angle light has been used in microscopy and industrial machine vision applications for the purpose highlighting defects or particles on relatively flat surfaces. This is sometimes referred to as “dark field illumination.” The fundamental concept is to use lighting at an angle to the surface such that anything that sits on or protrudes from the surface will scatter light up to an eye, a detector or a camera. Light that is reflected directly from the surface itself will never reach the eye, detector or camera. For noisy backgrounds or difficult to see objects, this concept can be taken to extremes such that the illumination source is at a very low grazing angle with respect to the surface. This can form an even higher contrast between the surface and any objects on the surface so that they can easily be detected. The low grazing angle minimizes any reflection from the flat surface while maximizing the reflection from the objects on the surface. In cases where the illumination is coming from a single direction, any objects on the surface will also cast a long shadow behind the object thus making them easier to find. Grazing angle is defined as the angle between a light beam and a surface (i.e. 90 degrees minus the angle of incidence). This concept has not been adapted for finding non-microscopic small particles on ordinary room sized surfaces.
There is a need for a cleaning tool which will optimally illuminate small items on a planar surface and provide a means for recovering said small items.
There is a need for a cleaning tool capable of resting flat on a planar surface and providing illumination with one or more light sources, which provide illumination of the surface in an area extending from immediately adjacent to the one or more lights and for a further distance from the one or more light sources, wherein said illumination is characterized by a low grazing angle that will illuminate small items on the planar surface. The light will also cast a long shadow behind any object (on the side opposite the light source).
There is a need for a cleaning tool capable of resting flat on a planar surface and providing illumination with one or more light sources, which provide illumination of the surface in an area extending from immediately adjacent to the one or more light sources and for a further distance from the one or more light sources, wherein said illumination is characterized by a grazing angle less than 10 degrees.
There is a need for a cleaning tool capable of resting flat on a planar surface and providing illumination—with one or more light sources, which provide illumination of the surface in an area extending from immediately adjacent to the one or more light sources and for a further distance from the one or more light sources—, wherein said illumination is characterized by a grazing angle less than 6 degrees.
There is a need for a cleaning tool capable of resting flat on a planar surface and providing illumination with one or more light sources, which provide illumination into areas with low ambient light levels such as under furniture, under a workbench, under an automobile or other darkened area.